This invention relates to envelope handling equipment and deals more particularly with such equipment for checking a plurality of envelopes for the presence of enclosed documents.
The device of this invention is somewhat similar in function to that of U.S. Pat. No. 4,016,980, filed May 9, 1975 and entitled DEVICE FOR CHECKING ENVELOPES FOR ENCLOSED DOCUMENTS, and is an improvement on the device disclosed therein.
As is also the case with the device described in the above-mentioned application, the device of this invention may be used in various different applications where it is necessary or desirable to inspect a large number of envelopes for the presence of enclosed documents and to segregate those suspected, as a result of the inspection, of containing documents. For example, many businesses, government agencies and other institutions have mail receiving or similar departments to which documents such as checks, bills, order forms, receipts and the like are delivered in sealed delivery or mailing envelopes. After receipt of the envelopes, they are opened and their contents extracted, and after such extraction they are normally considered waste and are suitably disposed of. The envelope opening and content extracting processes may be carried out either by hand or through the use of automatic machinery; but, in either case, it is possible that some mistakes may be made causing some forwarded documents to be unextracted from their envelopes and to be accordingly consigned to waste with the envelopes and destroyed. The device of this invention is particularly useful in this situation for checking previously opened and supposedly emptied envelopes and for retrieving those suspected of containing enclosed documents prior to their destruction.
Usually the envelopes involved are return mail envelopes provided by the addressee and are, therefore, all of similar size facilitating their handling by automated equipment. However, the envelopes may originate from various different manufacturers, or single manufacturers, using different paper stocks of highly different opacities. Therefore, the detection of enclosed documents by opacity sensing is complicated by the fact that the envelopes themselves may be of quite different opacity from envelope to envelope. The device of this invention is especially insensitive to such envelope opacity differences and, therefore, is particularly well adapted for use in those situations where such differences exist and are otherwise a problem.
The device of this invention makes use of the fact that a document enclosed in an envelope is normally substantially smaller in width than the envelope so that as a document containing envelope passes the inspection station either the top or bottom sensor, or both, will see a lesser opacity than the center sensor, and this difference is used to produce a suspect signal. In rare instances, however, the enclosed document may be of such width as to intercept all three opacity sensors when its envelope passes the inspection station. To provide for this contingency, the device of the invention also includes a means for producing a suspect signal in the event the opacity sensed by the center sensor exceeds a predetermined level for a predetermined time, thereby further augmenting the reliability of the device and making its error rate extremely small.
Other objects and advantages of the invention will be apparent from the following description and from the drawings forming a part hereof.